Quasi-experimental Design

Summary

This video script introduces quasi-experimental design, a non-random assignment study aimed at estimating the causal impact of interventions. It highlights the design's resemblance to true experiments but without random participant selection. The script outlines different types, including non-equivalent comparison groups, pretest-posttest, interrupted time series, and combination designs, using examples like teaching methods and class hours to illustrate their application in determining the effectiveness of interventions.

Takeaways

• 🔬 Quasi-experimental design is an evidence-based interventional study that uses non-random assignment to estimate the causal impact of an intervention.
• 📊 It aims to determine causal relationships among variables, similar to true experimental research but without random selection of participants.
• 📝 The design includes pre-tests and post-tests, with the control group being optional depending on the design specifics.
• 🎓 The main objective is to evaluate the effectiveness of a treatment or intervention on a target population.
• 👥 The non-equivalent comparison groups design involves two testing groups that are not randomly assigned, leading to potential internal threats to validity.
• 🎼 An example study assesses the effectiveness of a new teaching method for music theory in bachelor of cultural and arts education students.
• 📉 The pretest and posttest design tests the dependent variable before and after the intervention, identifying changes as a result of the treatment.
• 👨‍🎓 This design is applied to students with low cognitive levels in music theory, using a pre-test to identify participants and a post-test to measure intervention effectiveness.
• 📈 The interrupted time series design involves multiple tests before and after an intervention, allowing for the observation of consistency and effectiveness over time.
• 🕒 An example of this design is determining the effect of shortened class hours on student productivity, with observations before and after the intervention.
• 🔄 The combination design merges elements of non-equivalent and pretest-posttest designs, comparing improvements between a test group receiving treatment and a control group.
• 🎼 Another study example explores the effects of a new teaching method on students' attitudes towards music theory, using pre- and post-tests to measure changes.

Q & A

What is a quasi-experimental design?

A quasi-experimental design is an evidence-based interventional study that uses non-random assignment to estimate the causal impact of an intervention on a target population, aiming to determine causal relationships among variables.

How does quasi-experimental design differ from true experimental research?

Quasi-experimental design resembles true experimental research but differs in that there is no random selection of participants involved in the study.

What are the key components of quasi-experimental design?

Quasi-experimental design involves pre-tests and post-tests and may or may not include a control group, depending on the design.

What is the main objective of quasi-experimental design?

The main objective of quasi-experimental design is to evaluate the effectiveness of a treatment or an intervention.

What is the non-equivalent comparison groups design in quasi-experimental research?

The non-equivalent comparison groups design involves two testing groups that are not randomly assigned, which may lead to internal threats to the validity of the research results.

What factors might influence the results of a non-equivalent comparison groups design?

Factors such as the student's IQ level, student behavior, teaching strategy, and student environment might influence the results of a non-equivalent comparison groups design.

What is the pretest and posttest design in quasi-experimental research?

The pretest and posttest design tests the dependent variable before and after the intervention is given, allowing researchers to observe changes due to the intervention.

How does the interrupted time series design differ from the pretest and posttest design?

The interrupted time series design involves a series of tests at given intervals before and after an intervention, allowing researchers to observe the consistency of the test and verify the effectiveness of the treatment.

What is a combination design in quasi-experimental research?

A combination design combines elements of non-equivalent designs and pretest and posttest designs, involving a test group and a control group, with only the test group receiving the intervention.

What is the purpose of using both a test group and a control group in a combination design?

The purpose is to determine the extent of improvement between the test group and control group and to assess whether changes are caused by the treatment or other factors.

Can you provide an example of a quasi-experimental design study mentioned in the script?

An example given in the script is a study assessing the effectiveness of a new method of teaching music theory to Bachelor of Cultural and Arts Education students.

Outlines

00:00

🔬 Introduction to Quasi-Experimental Design

This paragraph introduces the concept of quasi-experimental design, an evidence-based interventional study that uses non-random assignment to estimate the causal impact of an intervention. It aims to determine causal relationships among variables and is similar to true experimental research but without random selection of participants. The paragraph also mentions the inclusion of pre-tests and post-tests and the optional nature of a control group, depending on the design. The main objective is to evaluate the effectiveness of treatments or interventions, and the paragraph proceeds to describe different types of quasi-experimental designs, including the non-equivalent comparison groups design, which involves two testing groups that are not randomly assigned and may be influenced by internal threats to the validity of the research results.

05:01

📚 Types of Quasi-Experimental Designs

This paragraph delves into the various types of quasi-experimental designs, starting with the non-equivalent comparison groups design, which is exemplified by a study assessing a new method of teaching music theory to students. It discusses the potential influencing factors such as student IQ levels, behavior, teaching strategy, and environment. The paragraph then introduces the pretest-posttest design, which tests the dependent variable before and after the intervention, using a case study involving students with low cognitive levels in music theory. The interrupted time series design is presented next, which involves multiple tests before and after an intervention to observe consistency and verify the treatment's effectiveness, exemplified by a study on the effect of shortened class hours on student productivity. Lastly, the paragraph discusses the combination design, which combines elements of non-equivalent and pretest-posttest designs, aiming to determine the extent of improvement between a test group and a control group, with an example of a study on the effects of a new teaching method on students' attitudes towards music theory.

Keywords

💡Quasi-experimental design

Quasi-experimental design refers to a type of research that seeks to establish causal relationships between variables by using non-random assignment of participants to groups. Unlike true experiments, this design does not involve random selection, which can introduce internal threats to the validity of the results. In the video, this concept is central as it outlines the framework for evaluating interventions without the strict control of a randomized experiment.

💡Evidence-based intervention

Evidence-based intervention is a practice that relies on scientific research to inform decisions about treatments or programs. In the context of the video, it is the type of intervention that is being evaluated within the quasi-experimental design to determine its effectiveness on a target population.

💡Causal impact

Causal impact denotes the effect that an intervention has on a particular outcome. The video discusses how quasi-experimental designs aim to estimate this impact, despite the lack of random assignment, by comparing the outcomes of different groups that have been subjected to an intervention.

💡Non-random assignment

Non-random assignment is a method of allocating participants to groups in a study without using a random process. The video script explains that this is a key characteristic of quasi-experimental designs, which can lead to potential biases in the results due to non-equivalent groups.

💡Pre-test and post-test

Pre-test and post-test are assessments conducted before and after an intervention to measure changes or effects. The script mentions that quasi-experimental designs often involve these tests to evaluate the effectiveness of an intervention, as seen in the example of the new method of teaching music theory.

💡Control group

A control group is a standard part of experimental research used as a baseline for comparison. In the video, it is noted that a control group is optional in quasi-experimental designs, which can affect the ability to isolate the effects of the intervention.

💡Non-equivalent comparison groups design

This design involves two testing groups that are not randomly assigned, making them non-equivalent. The script uses this as an example to illustrate how internal threats to validity, such as differences in student IQ levels or teaching strategies, can influence the study's results.

💡Internal threats to validity

Internal threats to validity are factors that can compromise the accuracy of a study's findings. The video script discusses how non-random assignment in quasi-experimental designs can lead to such threats, affecting the reliability of the causal impact estimation.

💡Interrupted time series design

Interrupted time series design is a variant of pre-test and post-test design that includes multiple observations before and after an intervention. The video provides an example of how this design can be used to assess the effect of shortened class hours on student productivity, allowing for the observation of trend changes over time.

💡Combination design

Combination design is a type of quasi-experimental design that combines elements of non-equivalent comparison groups and pre-test and post-test designs. The script describes how this design can help determine the extent of improvement between a test group and a control group, while considering whether changes are due to the treatment or other factors.

💡Treatment

In the context of the video, treatment refers to the intervention or program being evaluated for its effectiveness. The script uses the term to describe the new method of teaching music theory that is implemented in the study as an example of a treatment.

Highlights

Quasi-experimental design is an evidence-based interventional study that uses non-random assignment to estimate the causal impact of an intervention.

This design aims to determine causal relationships among variables without random selection of participants.

Quasi-experimental research involves pre-test and post-tests, with the control group being optional.

The main objective is to evaluate the effectiveness of a treatment or intervention.

Non-equivalent comparison groups design involves two testing groups with non-random assignment.

Internal threats to the validity of results may arise from factors such as student IQ levels and behavior.

Pretest-posttest design tests the dependent variable before and after the intervention.

Interrupted time series design involves multiple tests before and after an intervention to observe consistency and verify effectiveness.

Combination design combines elements of non-equivalent and pretest-posttest designs to determine the extent of improvement.

Example study: Assessing the effectiveness of a new method of teaching music theory to bachelor students.

Example study: Evaluating an intervention program for students with low cognitive levels in music theory.

Example study: Determining the effect of shortened class hours on student productivity.

Example study: Examining the effects of a new teaching method on students' attitudes towards music theory.

Quasi-experimental design can help identify factors that influence study results, such as teaching strategy and environment.

The design allows for the observation of changes in testing to verify the true effectiveness of a treatment.

Combination design helps to determine if changes are caused by the treatment or other factors.

Quasi-experimental design provides a method to evaluate interventions in situations where random assignment is not feasible.

Transcripts

[Music]

hey guys i am ryan and this time we'll

talk about the quasi-experimental design

quasi-experimental design is an

evidence-based interventional study that

uses non-random assignment to estimate

the causal impact of an intervention on

a target population

this kind of research design aims to

determine causal relationships among

variables

[Music]

in this research the site bears

resemblance to true experimental

research but differs

[Music]

take note that there is no random

selection of participants in quasa

experimental research design

[Music]

this research design also involves

pre-test and post-tests

[Music]

on this kind of research design the

control group is optional dependent on

the design

[Music]

now the main objective of quasa

experimental design is to evaluate the

effectiveness of a treatment or an

intervention

now let's proceed to the different types

of quasi-experimental design

the first one is the non-equivalent

comparison groups design which involves

two testing groups

it is considered as non-equivalent since

members of groups involved are not

randomly assigned

there may be factors that might

influence the result of the study

and these factors are considered

internal threats to the validity of the

results of the research

[Music]

in this design both groups will be given

the same treatment and will undergo post

tests

[Music]

now let's consider this study which aims

to assess the effectiveness of new

method of teaching music theory to

bachelor of cultural and arts education

students

now as i mentioned earlier there will be

two groups in this design

now both groups will undergo the new

method of teaching music theory

which will be considered as treatment in

this particular example

after the treatment is implemented both

groups will have a post test wherein the

results will be identified

now since the participants are not

randomly assigned there may be factors

that might influence the result of the

study such as the student's iq level

students behavior

teaching strategy

and students environment

now let's proceed to the next type of

quasa quasi-experimental design which is

the pretest and posters design

now this design tests the dependent

variable before the intervention is

given and after the intervention has

been given

now let's consider this example which

aims to either students with low

cognitive level in music theory with an

intervention program

now a group of participants will undergo

a pts to identify the students with low

cognitive level in music theory

now once the participants have been

identified they will undergo a treatment

or an intervention program

now as they finish they will now undergo

any posttest wherein the results will be

identified if they pass or fail

from here the researchers can now come

up with conclusions

now let's proceed to interrupt the time

series design which is a variant of

peta's postlet's design

this involves a series of testing at

given intervals before and after an

intervention has been given this design

conducts multiple tests before and after

the intervention which allows the

researcher to observe the consistency of

the test it also verify if the treatment

has been truly effective based on the

changes in the testing made

now here's a study which aims to

determine the effect of shortened class

hours on productivity of students

in this case the researcher will have

multiple observations before the

treatment is given which is the

shortened class hours after that another

multiple observations will be given

after the treatment has been given

from here

we can conclude that the treatment has a

positive effect on the productivity of

the students

lastly

here's a combination design which

combines the elements of both

non-equivalent designs and pretest and

post-test designs

this design involves a test group and

control group

both groups are given impedance but the

treatment is only given to one group but

both will have post deaths

the objective is to determine the extent

of the improvement between the test

group and control group

and the main question to determine is

whether the changes is caused by the

treatment or other factors here's

another study which is the effects of

new method and teaching music purely

towards students attitude on the subject

now here group a is the test group and

group b will be the control group

now both groups will have a pre-test to

determine their initial attitude on

music theory

however only the group a or the test

group will have the intervention or the

treatment

after the intervention has been given

both groups will have their posters to

determine if there's an improvement or

changes on their aptitude on music

theory

now that is quasi-experimental design

thank you